Telephone-repeater.



11.5, SHREEVE.

TLPHONE REPEATER.

Mmc/111011 men MA1/25,1911.

HERBERT E. SI-IREEVE, QF SHORT HILLS, NEW JERSEY, A.SSIG-NOR T WESTERNELECTRIC COMPANY, 0F NEW YORK, N. Y., A CORPORATION 0F ILLINOIS.

TELEPHONE-REPEATER.

Specification of Ietters Patent. Patented 001;,` `12, 1915,

Application tiled May 25, 1911. Serial No. 629,261.

To all whom t may concern:

Be it known that I, HERBERT E. SHREEVE, a subject of the King of GreatBritain, residing at Short Iilills, in the county of Essex and State ofNew Jersey, have invented a certain new and useful Improvement inTelephone-Repeaters, of which the following is a full, clear, concise,and exact description.

This invention relates to telephonie apparatus such as telephonerepeaters and its objects are to provide a structure adapted forreadyreplacement in telephone circuits, to provide simplified automatic meansfor maintaining adjustment of the working parts of such instruments, andin general to simplify and improve their mechanical construction.

In accordance with -one feature of the invention there is provided areceiver and transmitter mounted as a unit and having v terminalconnections which may beV readily and quickly madev or severed withoutdisturbing the fixed wiring of the circuit. More particularly thereceiving and transmitting elementsV are each individually removablymounted end to end upon a tubular block. Terminals extending through theblock from one end thereof to the other for the receiver and from oneelectrode of the transmitter arm are arranged to coperate with springclips upon a base or socket part adapted to receive the bloc'k. Thevibratory member of the transmitting element when thus assembled isinclosed within the cylindrical block and thus wholly removed fromoutside disturbing sounds and protected from mechanical injury. Theblock supporting the elements may be likened to a cartridge which by asimple movement may be withdrawn from its socket and immediatelyreplacedby another similar structure. The block surrounding andsupporting the elements is -provided with holes running from one endthereof to the other, which serve as air passages for ventilation andheat radiation. Preferably the base part is provided with heat radiatingplates, which serve to quickly dissipate the heat conducted from thecartridge part to the base part and to that end the surface contactbetween these parts is made quite cally relieving the pressure upon thegranuby packing of the granular carbon is prevented. The transmitter-element is provided with a thermostatic diaphragm and is connected in-circuit with the. receiver, the diaphragm being arranged -to bowoutwardly to relieve the pressure in the transmitter upon an increase ofcurrent in the circuit, the receiver being also adapted by magneticattraction to bow the diaphragm outwardly upon an increase of current inthe circuit.

The invention will'be' more fully understood by reference to theaccompanying drawings, wherein- Figure 1 is a transverse section on theline 1-1 of Fig. 2, and F 2 is a rear view of a telephone repeaterembodying features of the invention; Figs. 3 to 9 inclusive are detailviews of separate. parts of the repeater; and Fig. 10 is a diagramshowing'` of the base piece. Fitting over the exposed end of the block 2is a cap l having ventilating perforations 5, the'purpose of which willbe more fully explained hereinafter. The cap is adapted to be held vinplace by screws .6, engaging the ends'of elongated bolts 7 extendingoutwardly from lthe block 2. Interposed between the heads of the screw 6and the cap 4'is a fiat ring 8 and a 'distance piece 81 which togetherform a frame for a number or instruction card to be placed between itand the cap. The heads of the screws 6 are perforated tol receive" awire 7 8 which may be tied or sealed midway between the heads by a' leadseal 79. Formed integrally with thebase piece l are a series of heatradiating plates 9 and upon the rear side of the base are three contactsprings l0, 11 and 12 mounted upon insulating blocks 13. Circuitconnections to the frame and to the three contact springs 10, 11 and 12are made Athrough the binding post's 38, 39,40 and 41, respectively,these being mounted uponsegments; of insulating material as 42 (Fig. 8),and the latter three .thereof being4 insulated from the frame bysuitable bushings. Binding post 38 is in direct contact with the frame.The base has an overhang# ing flange 14 extending beyond the level ofthe contact springs and their retaining screw heads, this flange,however, being partly open at 15 to permit free circulation of air. Thethree contact springs 10, 11 and 12 eX- tend inwardly to points in linewith the Y socket opening and are each provided with a contact surface16, preferably of platinum. Coperating with the contact springs, whenthe block 2 is in place in the socket of the base piece l, are threecontact rods 17 18 and 19. Rods 18 and 19 extend through the `bloclr 2from one end to the other and are yto end serve as'air passages forventilation.

The plate 24 has a central opening through which the. contact rod 17extends, this rod serving to support an electrode plate 26, on the innersurface of said plate 24. The electrode 26 and rod 17 are insulated bysheets of mica 27 and 28 and held in place by a nut 29 and washer 80,the nut engaging threads on the rod 17. `This rod 17 serves also toelectrically connect the electrode with the contact spring 10.' Theelectrode plate 26 has a facing o-f carbon 30. Formed integrally withthe plate 24 is an externally threaded flange 31 which forms the sidewalls of a granular carbon transmitter button. The inner surface of thisflange is coated with insulating enamel.

The opposing electrode of the transmitter button is a vibratorydiaphragm formed of two thinplates of metal, the inner one,'32,

of gold and the outer one, 33, of iron. These plates are clampedtogether at their outer edges by an internally threaded flanged ring 34engaging the flange 31 of the plate 24. Centrally mounted. upon thediaphragm is an iron rod or pole piece 35 held in place by a gold platedscrew 36. The transmitter button thus constructed is partly filled asshown with granular carbon 37, the circuit through it passing fromthespring 10 to the contact 17 and thence by way of the electrode 26through the granular carbon 37, and the vibratory diaphragm 32, 33 tothe frame v1 and binding'post 38.

The receiving element of the repeater comprises a. cylindrical iron orsteel shell 43 fitting snugly within the block 2 and held in place by aset screw 44, a compound magnet sppol 45 of brass or other non-magneticmaferial, windings 46 and 47 thereon and an iron head 48. The spool isheld in place by a screw 49 passing through the side of the shell 43,and the head 48 is held in place against the outer end of thecshell" 43Aby scr/ews 50, 50. Extending centrally throilgh tht*l head 48 is a polepiece 51, the end of which is presented toward and lies close. to theend of the opposing pole piece 35. The pole piece 51 is enlarged andthreaded where it passes through the head 48 and is provided with ahexagonal head 52 and a nut 53 by means of which the air gap betweenpole pieces 51 and 35 may be adjusted. One terminal wire of each of thewindings 46 and 47 is connected to the central part of the spool headand is thus metallically connected to all parts of the frame ofthe-instrument. The other two ends 54, 55 of the windings are broughtthrough to the outer end of the spool and thence to the outside of thehead 48, being insulated therefrom by rubber bushings 56. These terminalwires 54 and 55 are connected to the outer ends of the contact rods 18,19 by means of terminal clips 57 and screws 58. The winding 47 beingfarthest away from the air gap between the electrodes is the magnetizing winding, while the winding 46 is the receiver winding. 1t willbe noted that the electrode rods 35 and 51 extend freely through acentral opening in the spool 45. With this construction the shell 43may, if desirable, be ofsteel and forma permanent magnet, in which casethe magnetizing winding would be omitted.

A suitable circuit arrangement for the telephone repeater hereindescribed is shown vin Fig. 10, wherein 59 and 60 are the main winding62 is included directly in the two line wires 59, 60 and from a centralpoint in this winding in each wire and bridged across the circuit isacondenser 63 in series with one winding of an input repeating coil comprising the windings 64, 65. The winding 65 is in a local circuit whichincludes a condenser 66 and the receiver winding 46 of the repeater,this circuit passing from the condenser 66 to the frame 1, thence toblock 2 in contact withv .the spool 45, winding 46, contact rod 19,contact spring 12, and input repeating coil winding 65. The connectionfrom the block 2 to the spool 45 is indicated in the circuit diagram bya dotted line 67. A local circuit is also provided for the transmitterbutton and the magnetizing winding 47 as follows: Afrom the groundedbattery 68 to the resistance 69, primary output repeating coil Winding61, COntact spring 10, contact rod 17, electrode 26, carbon granules 37,vibratory diaphragm 32, 33, block 2, spool 45, winding 47, contact rod18, contact spring 11 and impedance coil 71 to ground lll@ limit theflow of current in this local circuit vand that of the condenser 72 tolocalize the microphonic currents in the transmitter button and'toexclude such currents from the magnetizing Winding 47.

In operation vbice currents coming over the circuit of line wires 59, 60from either direction will, by -induction through the windings 64, 65,cause variations in the attractive forces between the pole pieces 5l and35 of the receiver, thereby causing corresponding variations 4in theresistance of the transmitter button land of current inthe localtransmitter circuit. This local circuit includes the primarv winding 61of the output repeating coil which thus causes a rein- 1forcement of thetelephonic currents in the The action of the .gold and iron diaphragm ofthe transmitterbutton is such that any tendency of the carbon granulesto pack will cause said .diaphragm to move away lfrom the opposingelectrode, thereby relieving the pressure and maintaining thetransmitter button in a sensitive state or condition. Gold has a highercoefficient of expansion than iron and gives a good contact surface forthe carbon granules, while iron serves as an element of the thermostatand as a part of the magnetic. circuit of the receiver. Other metals oflike characteristics may be used in. place of gold and iron, if desired.The gold plate lying next to the granules and expanding more rapidlythan the iron, the diaphragm bows inwardly upon any increase intemperature in the granular chamber and conversely bows' outwardly upona vdecrease in the temperature. The granular button being connected "incircuit through a resistance, there is at rst a gradual increase intemperature in the granular' carbon which continues until a fairlyuniform temperature is reached. During this period there is therefore agradual inward bowing ofthe diaphragm. This action is, however, followedby a tendency of the granules to pack, whereupon the heating decreasesdue to the lowered resistance of the granular button. This decrease intemperature resultsin a cooling of the diaphragm and'thus a movement 'ofthe diaphragm outwardly, whereupon the granules are relieved ofpressure, the resistance and temperature are increased and thediaphragmis again moved inwardly. It has been found in practice that a`.diaphragmconstructed in this manner has a periodic movement forward and backward,the period being of about thirty to forty seconds duration. Themovement, although extremely slight and vimpossible of directobservation is sui'licient to keep the carbon granules in a free andsensitive state. It may be made manifest by placing a' milammeter in thelocal transmitter circuit. With a current ofabout400 mil-amperes in thecircuit the needle shows a periodic movement of about twenty milamperes,that is to say, from about 380 to 400 mil-amperes.

not only by heat generated in the granules, but also by magnetic pull ofthe magnetizing winding of the receiver. These two forces in fact worktogether or cooperate to relieve the pressure on the granules upon anytendency thereof to pack. v

It is in practice frequently found desirable to replace one instrumentwith another and by the arrangement herein described,

ythis can be readily done without disturbing the circuit connectionsother than to separate the contact rods of the removable partfrom thefixed contact springs ofthe base.

The thermostatic diaphragm being partly of iron, is acted upon- It isonly necessary that the transmitter and e receiver elements be removedas a unit from the frame l, the connections being broken at four points,three being between the contact rods 17, 1 8 and 19, and the contactsprings 10,11 and l2, and the fourth between the block 2 and the framel. The parts thus removed comprise the transmitting and receivingelements ltogether with the mounting block 2. Either of these elementsmay be separately removed from the block and replaced by a like element.The transmitter may be removed upon loosening the bolts 7, and likewisevthe receiver upon loosening thevset screw 44 and the connectingscrews58. The locking pin 3 serves to locate the removable elements intheir proper position so that it is impossible to make incorrectconnections when replacing one in-v strument with another.

When assembled complete'. as shown in Figs. land 2 and mounted upon awall or other support the heat generateolV in the l transmitter and'receiver elementsis dissipated partly by means -of the radiating plates9 and partly by the free circulation of air through the openspaces at l5in the base 1, the holes 25 1n the block 2, and the holes 5 in the,capfl.

I claim:

l. In a telephone repeater, the lcombination of a frame comprisingcontact springs and binding posts, of a block, transmitting andreceiving elements mounted therein,

2. In a telephone repeater, the combination with a frame comprising abase and socket, contact springs and Abinding posts,' of a cylindricalblock, transmitting and receiving elements secured to sairr block,terminals for said elements mounted upon said block, said block beingadapted for kinsertion in the socket of said frame in position forengagement, of said terminals with said contact springs,l and apinfcarried by said block and registering with a slot in said socket tolock said block Within said socketf` 3. In a telephone repeater, thecombination of a frame having contact springsand a heat radiator, of ablock adapted toengage said frame, transmitting and receiving elementsmounted upon saidjblock and ter. minal connections upon said block forsaid elements adapted to engage said contact springs.

f1. In a telephone repeater, the combination of an electromagneticreceiver "and a granular transmitter placed lin operative relation tosaid receiver, said transmitter having a thermostatic diaphragm andbeing connected in circuit with said receiver, said diaphragm beingarranged to bow outwardly and thereby to relieve the pressure on thegranules in said transmitter upon an increase of current in said circuitand said receiver being also adapted by magnetic attraction to bow saiddiaphragm outwardly upon an increase of current in said circuit.

5. In a telephone repeater, the combination of a receiver having amagnetizing winding and a granular transmitter in operative relation* tosaid receiver, said transmitter having a thermostatic diaphragm formingone Wall Aof the granular chamber, and a local circuit including saidmagnetizing Winding and said transmitter, said thermostatic diaphragmand said magnetizing Winding being arranged and adapted jointly torelieve the pressure on the granules of said transmitter upon a tendencythereof topack by causing said diaphragm to bow inwardly.

6. In a telephone repeater, the combination with an electromagneticreceiver and agranular transmitter in operative relation thereto, theWinding upon said receiverbeing connected in series with said buttonandV a thermostatic diaphragm adapted under the influence jointly of theheat generated in said transmitter and ofthe magnetc pull of saidreceiver to relieve the transmitter granules of pressure upon a tendencythereof lto pack.

7. In a telephone repeater, the combination with an electromagneticreceiver and a granular transmitter in operative relation thereto, thWinding upon saidv receiver being connected in series with said buttonand a` thermostatic diaphragm, onej element of which is iron, adaptedunder the influence jointly of the heat generated in saidtransmittcrfand of the magnetic pull of said receiver to relieve thetransmitter granules of pressure upon a tendency thereof to pack.

8.-.Ina telephone repeater, the combination with a transmitterv and areceiver, of a tubular block within which saidtransmitter and receiverare mounted, a lgsupporting' base, and a cap, said base and cap forminga lcomplete inclosure for said ;block, and said block having holesextending from said base to said cap, for the free circulation of airand dissipation of heat.

9. In a telephone repeater ,fthe combination of a granulartransmitterfhaving as one wall of the granular chamber a thermostaticdiaphragm composed in part of iron,

and an electromagnetic receiver arranged in operative relation to saiddiaphragm.y

10. In a telephone repeater, the combination with a base part, of ablock, and a transmitter and a receiver mounted on said block, saidblock, transmitter andk receiver forming a unit removably mounted onsaid base, and said transmitter. andreceiver being separately andindependently removable from said'block. A

11. 4In -a telephone repeater,theA combination with a socket base part,of a plug, and a transmitter and a receiver mountcd in said pluginoperative relation, tofy each other,

i said plug, transmitter and receiver forming a unit removably mountedin said socket base part, and said transmitter,l and receiver beingseparately and independently removable from said plug. j

12. In a telephone repeater, :jthe combination with a base part havingterminal c0n tacts, of Aa block having coperating contacts and arrangedto-be removably supported upon said base part, a transmitter and areceiver, said transmitter' and receiver being connected to saidcoperagting contacts and being separately and removably mounted on-saidblockin operative relation to each other.

In witness whereof, I hereunto subscribe my vname this 23rd day of May,lA. D. 1911.

HERBERT E. sHZREEvE.

Vlfitnessesz IRVING MACDONALD, y FRANK A. FLEISCHMAN.

